Best Bong for pro stoners. State of the art filtration with this dual function Sprinkler & Inline Perc Glycerin Filled Coil Oil Rig Bong. 13.4 Inch Glycerin Coil Bong with a unique Sprinkler Perc. Inline Perc to Sprinkle Perc to Glycerin Chiller Freezable Coil is very professional. 18mm Joint comes with domeless ceramic dab nail and cap.